Mailing machines including postage metering systems are known in the art including the DM SERIES of mailing machines available from Pitney Bowes Inc. of Stamford, Conn. Internet based postage delivery systems and data center services are also available from Pitney Bowes Inc. A postage metering system applies evidence of postage, commonly referred to as postal indicia, to an envelope or other mailpiece (directly or on a label to be applied thereto) and accounts for the value of the postage dispensed.
Postage metering systems are often categorized as closed system meters or open system meters. In a closed system, the system functionality is typically dedicated to postage metering activity and often includes a dedicated printer securely coupled to a Postal Security Device PSD postage vault. In an open system, the printer is typically not dedicated to the metering activity and is often connected to a remote Postal Security Device PSD postage vault or virtual PSD. In the open system defined by the United States Postal Service (USPS) Information Based Indicia Program (IBIP), indicia printed by the non-dedicated printer are made secure by including elements o addressee information in the encrypted evidence of postage printed on the mailpiece for subsequent verification.
Digital printing postage meters have removed the need for the physical inspection that was required with analog systems by cryptographically securing the link between the accounting and printing mechanisms. In essence, digital printing postage meters create a secure point-to-point communication link between the accounting unit and printhead. In such digital closed systems, the dedicated printer and the metering (accounting) device may be located in the same device and/or at the same location when placed in operation. Alternatively, the dedicated printer may be located in a first location (i.e., the local location where indicia are to be printed), and the metering (accounting) device may be located in a remote location, such as a provider's data center. In the latter situation, it is still necessary for the dedicated printer to be a secure device having cryptographic capabilities so that postage printing information, such as an indicium, received from the metering (accounting) device, and the metering (accounting) device itself, can be authenticated.
A method and system for dispensing virtual stamps is described in U.S. Patent Application Publication US 2003/0074325 A1 entitled Method and System for dispensing Virtual Stamps by Ryan that was published on Apr. 17, 2003 (the Ryan '325 application) and that is incorporated herein by reference. A Virtual Stamp Dispensing Metering VSDM system is described wherein indicia of varying values are calculated at a remote data center and downloaded to a mailing machine. The VSDM system stores the indicia and dispenses the indicia as needed. The system includes a secure storage unit and a state indicator that is used to prevent fraudulent reuse of the virtual stamps. A status field for each indicium record, i.e., Issued or Unused, is maintained to indicate whether an indicium has been issued (printed) or not. Accordingly, the VSDM system does not require sophisticated cryptographic processing because the indicia are signed at the remote data center. A network communication system may be used to efficiently download stamp information from the remote data center (with Virtual PSD) to the stamp dispensing metering system.
Many networks including the traditional Public switched Telephone Network have been designed that provide a dedicated path or circuit from source to destination for the duration of message transfer. The message is delivered along the same path in order and in its entirety. However, many communications networks such as the Internet have been designed that provide connectionless packet switched networks that usually send portions of a message or packet along different routes through the core of the network from the source node at the edge of the network to the destination node at the edge of the network. A packet switched network is sometimes operated in a connection-oriented reliable service manner such that it guarantees that the packets of the message are delivered in order and the message is delivered in its entirety. In other configurations such as media streaming applications, networks are operated as a connectionless unreliable service such that some packets may not be properly transferred and are not resent.
A network communications protocol defines the control and data message format and order. Information exchanges between computers may fail for a variety of reasons. The most common remedy is to attempt to retry, or resend the message. The exchange of information between a postage evidencing device and a data center may fail resulting in loss of funds or valuable information. For example, a request to purchase postage may not be completed during its transmission over the Internet (e.g., no explicit acknowledgement is received). In such a situation, the sender does not know if the original request was received by the data center or not. As a result, the same request may be resent. If the data center did receive the initial request and the failure was due to an acknowledgement not received by the sender (on time), then the data center may assume that two distinct purchase orders where issued by the same customer, in which case the customer is charged twice.
Similarly, if the transmission of the fulfillment message from the data center to the customer were interrupted, the data center would not receive an explicit acknowledgement from the customer. The data center might then resend the message. In such a situation, the customer would receive twice the value that he paid for. In many cases, the solution used to solve this problem is to require an acknowledgement for each transaction before declaring it complete. However, in this case, depending on the scenario, either the customer of the data center may lose funds due to lack of trust (requiring an acknowledgement to complete the transaction). Additionally, such systems typically require end-to-end acknowledgements and serial transfer of messages of information of value. Systems that implement complex safeguards against lost messages in most cases have cumbersome user interfaces which make them un-appealing to the average user.
Accordingly, there is a need for systems and methods for reliable transfer of messages of information of value between a remote data center and a local device that accommodate resend requests, that are not limited to serial transfer and that are not limited to end-to-end acknowledgements.